Abstract

While metastatic breast cancer (MBC) remains incurable, a vast array of active therapeutic
agents has provided the opportunity for long-term disease control while maintaining
quality of life and physical function. Optimal management of MBC balances a multitude
of factors, including a woman's performance status, social support, symptoms, disease
burden, prior therapies, and surrogates for tumor biology. Choosing the most appropriate
initial therapy and subsequent sequence of treatments demands flexibility as goals
and patient preferences may change. Knowledge of the estrogen receptor (ER), progesterone
receptor (PR), and Her2 receptor status of the metastatic tumor has become critical
to determining the optimal treatment strategy in the metastatic setting as targeted
therapeutic approaches are developed. Patients with ER+ or PR+ breast cancer or both have a wide array of hormonal therapy options that can forestall
the use of cytotoxic therapies, although rapidly progressive phenotypes and the emergence
of resistance may ultimately lead to the need for chemotherapy in this setting. So-called
'triple-negative' breast cancer - lacking ER, PR, and Her2 overexpression - remains
a major challenge. These tumors have an aggressive phenotype, and clear targets for
therapy have not yet been established. Chemotherapy remains the mainstay of treatment
in this group, but biologically based clinical trials of new agents are critical to
developing a more effective set of therapies for this patient population.